The poll, conducted by the Tarrance Group and Lake Research, also finds that 25 percent of Americans have an unfavorable impression of the Kochs, while 12 percent have a favorable one. Eleven percent had no opinion.

Senate Majority Leader Harry Reid has led the Democratic push to make the brothers a major target in the upcoming midterm elections in an effort to tie the GOP to big business and big donors.

“I believe in an America where economic opportunity is open to all. But based on their actions and the policies they promote, the Koch brothers seem to believe in an America where the system is rigged to benefit the very wealthy,” Reid said in a floor speech earlier this month.

Reid has a 35 percent unfavorable rating, according to the poll.

The coordinated attack on the Kochs — who have poured millions of dollars into conservative and libertarian causes over the years — is part of an an appeal to the party’s liberal base. The poll shows that liberal Democrats are more likely than the general public to know about the Kochs.

Among self-identified liberal Democrats, only 43 percent had never heard of the Kochs — 9 points lower than the general public. And 45 percent had a negative opinion of the two brothers — 20 points higher than the general public.